Fix: Use Multi.run for game update in transaction

Changed from Multi.update to Multi.run to properly use the existing
update_game function which handles changeset creation.

Signed-off-by: immortal71 <newaashish190@gmail.com>

Author: immortal71

copi.owasp.org/lib/copi_web/live/game_live/show.ex

@@ -84,8 +84,9 @@ defmodule CopiWeb.GameLive.Show do
               player_id: Enum.at(players, rem(i, player_count)).id
             })
           end)
-          |> Ecto.Multi.update(:start_game, 
-            Copi.Cornucopia.change_game(game, %{started_at: DateTime.truncate(DateTime.utc_now(), :second)}))
+          |> Ecto.Multi.run(:start_game, fn _repo, _changes ->
+            Copi.Cornucopia.update_game(game, %{started_at: DateTime.truncate(DateTime.utc_now(), :second)})
+          end)
 
         # Execute transaction: all cards dealt and game started, or nothing happens
         case Copi.Repo.transaction(multi) do